Adjustable tap.



AJB. CARLL.

ADJUSTABLE TAP.

APPLICATION I'YILED rm. 7, 1 10,

Patented Dec. 6, 1910.

ADDISON B. CARLL, OF MOBILE, ALABAMA.

ADJUSTABLE TAP.

Specification of Letters Patent.

Patented Dec. 6, 1910.

Application filed February 7, 1910. Serial No. 542,464.

To all whom it may concern:

Be it known that I, ADDISON B. GARLL, a citizen of the United States,residing at Mobile, in the county of Mobile and State of Alabama, haveinvented a new and useful Adjustable Tap, of which the following is aspecification.

This invention relates to taps for forming interior threadson pipefittings or flanges or similar articles, and has for its object theprovision of a simple and strong construction whereby the tap may bemade nearly straight, but so that it may be expanded, cut ting thethread little by little until the full size is obtained withoutnecessitating undue labor in turning the tap.

The stated object and such other objects as will hereinafterincidentally appear, are attained by the use of the device illustratedin the accompanying drawings, and the invention consists in certainnovel features of the same which will be hereinafter first fullydescribed and then specifically pointed out in the appended claim.

In the drawings, Figure 1 is an elevation of a tap embodying myimprovements. Fig. 2 is a longitudinal section of the same. Fig. 3 is atransverse section through the head of the mandrel.

The mandrel comprises a head 1 and a shank 2, having a threaded portion3, as shown. The head 1 is provided with a plurality oflongitudinallydisposed grooves which are substantially V-shaped in crosssection and communicate with longitudinal slots leading to the outersurface of the head, the bases of the grooves converging toward theouter end ofthe head. The cutters 4 are provided on their outer edgeswith the usual cutting teeth 5, and their inner edges are tapered orbeveled as shown at 6, so as to fit within the V-shaped longitudinalgrooves in the head and are expanded beyond the sides of the body of thecutter so as to provide shoulders 7 which engage against the outer wallsof the longitudinal grooves in the head of the mandrel and,consequently, prevent the cutters slipping radially from theirengagement with the mandrel. By employing this tapered or V-shaped construction of the cutters and the longitudinal grooves in the mandrel, Iam enabled to employ a large number of cutters in a single mandrel and,consequently, accomplish the threading of the pipe fitting or nut moreexpeditiously than has been heretofore possible.

The inner ends of the cutters are provided with longitudinallydisposedoverhanging hooks or lugs 8 whichare adapted to engage over a flange 9and in an annular groove 10 in a nut 11 which is mounted on the threadedportion 3 of the mandrel and is adapted to be moved longitudinally ofthe mandrel by reason of said threaded engagement, as will be readilyunderstood. By rotating the collar or nut 11 so as to move it away fromthe head of the mandrel, the cutters will be caused to movelongitudinally of the head and toward the wider end thereof so that theywill be expanded or moved radially outward upon the said head and,consequently the cutting edges may be formed without much taper, but thedie may be set in to start in the ring which is to be tapped andgradually expanded out, cutting the thread little by little until it isthe required size without undue labor. This construction and arrangementof the parts ef fects a positive and rapid adjustment of the cutters andat the same time supports them firmly in operative position in all theiradjustments. The exact engagement of the cutters with the adjusting nutillustrated and just described is preferred by me owing to the facilitywith which the parts may be assembled, but it will be understood, ofcourse, that the arrangement may be reversed and the hooks on thecutters made to engage an internal groove in the nut without involvingany departure from the invention.

By referring to Fig. 3 of the drawings, it will be noticed that the headof the mandrel is cut away to a comparatively slight extent so that astrong support is provided for the cutters, and that the taperedformation of the inner edges of the cutters permits the head to beconstructed in very nearly an un- .mutilated form, so that while a largenumber of cutters may be supported in the head, the structure will notbe weakened in any degree.

Having thus described the invention, what I claim as new, and desire tosecure by Letters Patent, is

The combination of a mandrel having a head provided with a series ofconverging longitudinal V-shaped grooves, and a corresponding series ofstraight -walled radial longitudinal slots leading outward from the saidgrooves, the apex of the V-shaped grooves facing the center of the headand the said slots being narrower than the widest or outer part of saidgrooves, a series of cutters having tapered enlarged inner edges snuglyfitting in the said V-shaped grooves, and longitudinal lateral shouldersbearing against the outer Walls of the said grooves, the sides of thecutters beyond the said shoulders being straight and parallel to fit inthe straight Walled radial slots of the mandrel, and means for adjustingthe cutters longitudinally of the grooves and slots.

In testimony, that I claim the foregoing as my own, I have heretoafiixed my signature in the presence of tWo Witnesses.

ADDISON B. GARLL.

\Vitnesses GLENN L. HAMBURGER, D. S. VINCENT.

